The first meta-analysis to specifically examine the dose-response relationship between physical activity and risk reduction for coronary heart disease (CHD) found that the most benefit for CHD risk occurs at very modest, achievable levels of physical activity, says a Heartwirearticle based on a study published online this month in Circulation.

This review included 26 studies published in English since 1995, 9 of which allowed for quantitative estimates of leisure-time physical activity.

According to the data, people who engage in the equivalent of 150 minutes of moderate-intensity exercise per week—the basic minimum as recommended by 2008 US federal guidelines—had a 14% lower CHD risk, and those who achieved 300 minutes per week had a 20% lower risk of CHD, compared with sedentary individuals. People who engaged in more than the advanced amount of exercise (750 minutes per week of moderate intensity exercise; 5 times the minimum recommended amount) had about a 25% reduction in risk of CHD.

In addition, the researchers found that people who were physically active at levels lower than the minimum recommended also had a significantly lower risk of CHD, compared with people who did were not active at all.
The cardiovascular benefits of exercise appeared to be stronger in women than in men, although the authors say they don't have any plausible explanation for this finding. Also, there were insufficient data to examine the effect of age at baseline or race on the relationship between physical activity and CHD risk, the article says.